Dual controlled switch



March 21, 1939. B. E. SHAW 2,151,233

DUAL' CONTROLLED SWITCH Filed Dec. 8, 1956 2 Sheets-Sheet lv l I G90 0 52 W v W hmg r MarcB 21,1939. B. E. SHAW 2,151,238

DUAL CONTROLLED SWITCH Filed Dec. 8, 1956 2 Sheets-Sheet 2 IO as Patented Mar. 21, 1939 PATENT orrlcs 2,151,238 DUAL con'rnomno swr'rou Burton E. Shaw,

Adel, Iowa, assignor to Penn Electric Switch (10., Des Moines, Iowa, a corporation of Iowa Application December 8, 1936, Serial No. 114,849

8 Claims.

One object of my present; invention is to provide a compact switch arrangement in which there is a normal operator and a safety operator so combined and associated that the safety operator can open the switch independent of its normal operation any time that a predetermined abnormal condition exists in the system being controlled by the control switch.

A further object is to provide a switch adaptable for refrigerating service or the like which is normally responsive to the temperature of an evaporator coil, a safety device being provided which is responsive to an excessive pressure in the refrigerant system to act as a safety device at such times and open the compressor motor cir cuitupon operation oi the safety device, regardless of the position of the temperature controlled portion of the switch.

Still a further object is to provide such a switch in which a contact unit is readily changeable without the necessity of having to disconnect the refrigerant line or temperature bulb connection, anything goes wrong with the switch, it being merely necessary to remove two screws, place a substitute switch in position and replace the screws.

Still a further object is to provide a switch of the character disclosed in which range and differential adjustment are secured and. readily var iable and in which the mechanism responsive to an excessive pressure to act as a safety device can be set for any predetermined pressure within its range and when such pressure is reached a toggle or snap acting mechanism. opens the switch even though the automatic mechanism is calling for aclosed position thereof.

With these and other objects in view, my invention consists in the construction, arrange ment and combination of the various parts of 4 the device, whereby the objects contemplated are attained, as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanying drawings, in which:

Figure l is a side elevation of my dual controlled switch showing the cover removed.

Figure 2 is a sectional view on the line iZ--2 of Figure 1.

Figure 3 is a sectional view on the line 3-3 of Figure 1 showing the safety device oi the switch.

Figure 4 is a view similar to a portion of Figure 2 showing how the contact unit which I use in connection with my switch can be associated with the switch for reverse action when the contrailer is to be usedfor a. different purpose.

. the arm 56 against the head of the screw 4 2;

Figure 5 is a sectional View on the line 5-5 of Figure 2.

Figure 6 is a sectional View on the line t-ti of Figure l; and

Figure 7 is a sectional view on the line of Y 5 Figure 5.

On the accompanying drawings 32 have used the reference numeral ill to indicate a housing for the mechanism of my switch. housing it is provided with an extension hou, ing li having m the usual conduit opening it through which the wires may be brought for connection to the contacts or the switch.

Within the housing it there is provided a chain nel shaped frame it which is rigidly mounted rel- 5 ative to the housing. There is provided a knife edge bearing plate it against which i seats 2t of an actuating arm 22 engage. The arm 22 is constrainedto move counter-clockwise in Figures 2 and 6 by a range adjustment spring 20 the adjusting screw of which is indicated at The opposite end of the arm is limited to movement through a slight are by reason of such opposite end extending into a slot (it of the stationary frame it, which slot limits the movement 25 of the arm 22 as shown by the closed and open. switch positions respectively of these two figures (Figs. 2and 6).

A normal actuator is provided for the arm comprising a bellowshousing til having therein a bellows 32. The bellows 32 is operatively connected, by a'rod 3t and an adjustable point to the arm 22.

A spring 3% within a cupped base plate of the bellows 3'2 tends to retain the point 38 against 35 The bellows 32 is mounted in up "position to the spring 25 and by tightening the screw Ed, the operating range will occur at a higher pressure on the bellows t2 and vice versa.

The arm 2'2 is provided with an extension til having an adjusting screw M. The head of the adjusting screw is adapted to contact with the lower surface of a rock. arm 46 pivoted at it.

A light spring 56 tends to retain the roclc arm The end 45 of the rock arm opposite the screw it contacts with an operating pin 52 of a contact unit, which unit is shown in detail and claimed in my co-pending application Serial No. 81,701, filed May 25, 1938. to

In general, thecontact unit comprises a base 54 and a cover 56, the two being retained together by screws 58 which extend through both of them and are then screwed into the mounting plate 16 as' shown by dotted lines in Figure 4. 55

Within the cover 56 and mounted on the base 54 is a permanent horse shoe magnet 68 for attracting an armature 62 of a switch arm 64. The

switch arm 64 has a V seat engaging a knife edge bearing 85 of a bracket 66. The pin 52 is adapted to swing the switch arm 64 about the knife edge 65 as a pivot whenever the pin is pressed down'far enough for a spring 81, interposed between the pin and switch arm, to be compressed sufficiently to overcome the pull of the magnet 68 on the armature 62.

The switch arm 64 is connected with a contact spring 68 to lift a contact III carried thereby from a stationary contact I2 after the switch arm 64 has moved from closed circuit position. The V seats of the arms 22 and 64 are retained closely adjacent the knife edge bearings I8 and 65 by lugs I9 and 14 respectively.

I provide means for adjusting the differential of operation'of the switch at its high temperature position comprising an arm I6 pivoted at 18 and having a finger 80 engaging the arm 42 adjacent its open switch position, as shown in Figure 2. The arm 42, however, disengages the finger 80 in the open switch position of Figure 6, in which a stop lug 82 of the differential arm 16 has engaged the upper flange of the bracket I6. Such engagement is secured by a spring 84 which is made adjustable by a screw 86 for changing the upper limit or the widening differential of operation of the switch. Thespring must be picked up and stretched as a result of the power of the bellows 32 when the switch is in closed position as in Figure 2.

The rock arm 46 is provided with a lateral extension 88 extending through an opening 98 in the back of the bracket I6. Figure 3 being a sectional view of the bracket, shows this extension in 'cross sectionand shows a safety bellows 9| cooperating therewith through the medium of a toggle or snap acting mechanism. The bellows 9| is enclosed in a housing 92 and its compression is opposed by a spring 94 within the housing.

An actuating pin 98 extends from the head of the 48- bellows and bears against a'triangular shaped lever 98 which is pivoted at I80 to a stationary bracket I82. The toggle lever I84 is also pivoted to the bracket and an over-center spring I06 connects the actuating lever 88 with the toggle lever I84.

Normally the parts are in the full line position of Figure 8 but upon excessive pressure the arm 88 is swung against the bias of a spring I88 to the dotted line position, thus causing the spring I48 to pass ove center and as a result thereof the outer end of the toggle lever- I84 engages the extension 88 of the rock arm 46 for opening the switch contacts I8 and 12. The pressure at which this safety device will operate can be adjusted by an adjusting screw III! for the spring I 88.

In Figure 4, I illustrate how the switch can be adapted for reverse operation, that is, for opening the circuit on an increase rather than decrease in pressure. The rockarm 48 of Figure 2 is omitted and the contact unit turned end for end so that the actuating pin 62 thereof is contacted directlyby the head of the screw 44 instead of by the opposite end of the rock arm 46.

' Rractical operation The switch illustrated in Figures 1, 2 and 3 to '7 s adapted for controlling refrigerating mechanlsm, the bellows housing 88 being connected with a capillary tubeand bulb in the ordinary manner and the bellows housing '82 being connected with suitable piping to the outlet or high pressure side of a refrigerant compressor. During normal operation the refrigerant compressor motor will-be started and stopped in accordance with the temperature or pressure affecting the bellows 32 (closing with high pressure).

When an abnormal condition occurs, however, such as the'refrigerant line becoming clogged, the excess pressure resulting therefrom will trip the over-center toggle arangement in Figure 3 from its full line position to the dotted position, whereupon the switch will be opened and maintained open, regardless of any attempt of the bellows 32 to close it.

Since the lower surface of the right end of the rock arm 48 in Figure 2 contacts with the head of the screw 44, this end of the rock arm can ra'iseto the dotted position without biasing the arm 46 toward a raised position. Thus the safety control operates independent of the normal control and will permit operation of the refrigerating system again only after the trouble has been taken care of so that the high pressure condition will be removed.

Where the control switch is to be used for a heated rather than a cooled space, the switch can be reversed in action, as shown in Figure 4,

in a very convenient manner.

As to the switch contacts being in the form of a unit, this, from a service standpoint, is very desirable. If anything goes wrong with the switch contacts, the entire switch can be readily removed and replaced by another one in a matter of only a minute or two. This can be done without the necessity of having to pump down the refrigerant system as is necessary with many type of controller structures.

Some changes may be made in the construction and arrangement of the parts of my device without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use or mechanical equivalents, which may be reasonably included within their scope.

I claim as my invention:

1. In a control switch of the character described, a supporting member having a knifeedged bearing, a switch actuating arm having a V-seat seated thereagainst, condition responsive means for positioning said switch actuating arm, switch contacts controlled by said switch actuating arm and means comprising a hooklike finger extending from said switch actuating arm for retaining said V-seat closely adjacent said knifeedged bearing said finger engaging said supporting member at a point opposite said knife-edged bearing.

2. In a control switch of the. character described, a supporting member having a knifeedged bearing, a switch actuating arm having a V-seat seated thereagainst, condition responsive means for positioning said switch actuating arm, switch contacts controlled by said switch actuating arm and means for retaining said V-seat closely adjacent said knife-edged bearing, said means comprising a finger extending from said switch actuating arm and positioned back of said knife-edged bearing.

3. In a control switch of the character described, a supporting member having a knifeedged bearing, a switch actuating arm having a V-seat seated thereagainst, condition responsive means for positioning said switch actuating arm, switch contacts controlled by said switch actuating arm and means for retaining said V-seat closely adjacent said knife-edged bearing, said means comprising a finger extending from said knife-edged bearing and positioned back of said V-seat.

4. In a control switch of the character disclosed, a supporting member, an actuating arm pivotetd relative thereto, condition responsive means for controlling the position of said actuating arm, a rocker arm, coupling means between ,said actuating arm and said. rocker arm, a difierential widening arm engaged by said actuating arm adjacent one limit oi its movement, a contact unit including a mounting member, contacts mounted thereon and an actuating element for the contacts, said mounting member being adapted to be alternatively mounted with said actuating element operatively engageable with .said actuating arm for movement in a predetermined direction thereby or with said rock'er arm for reversing the movement of said actuating element relative to the movement of said actuating arm.

5.,In a control switch of the character disclosed, asupporting member, an actuating arm pivoted relative thereto, condition responsive means for controlling the position of said actuating arm, a rocker arm, coupling means between said actuating arm and said rocker arm, a differential widening arm engaged by said actuating arm adjacent one limit ofits movement, a contact unit including a mounting member, contactsmounted thereon and an actuating element for the contacts, said mounting member being adapted to be alternatively mounted with said actuating element operatively engageable with 35 said coupling means for movement in a predetermined directionthereby or with said rockerv arm for reversing the movement 01' said actuatingelement relative to the movement'of said acj tuating arm. 6. In a control switch or the character disclosed, a supporting member, an actuating arm pivoted relative thereto, condition responsive means for controlling the position of said actuating arm, a rocker arm, coupling means between said actuating arm and said rocker arm, a contact unit including a mounting member, contacts mounted thereon and an actuating element for the contacts, said mounting member being adapted to be alternatively mounted with said actuating element operatively engageable with said actuating arm for movement in a predetermined direction thereby or'with said rocker arm for reversing the movement of said actuating element relative to the movement of said actuating arm, and an auxiliary control for said actuating element comprising a pressure responsive element and snap acting means operable thereby upon an abnormal pressure affecting said pressure responsive element.

7. In a control switch of the character disclosed, 1 an actuating arm, condition responsive means for controlling the position of said actu-' ating arm, a rocker arm, one end of said rocker arm being operable by said actuating arm, a contact unit, an actuating element therefor, said contact unit being adapted to be alternatively mounted with said actuating element engageable with and operable by said one end of said rocker arm'or with said actuatingclement engageable with and operable by the other end of said rocker arm for reversing the movement of said actuating element relative to the movement of said ac tuating, arm, and an auxiliary control for said actuating element comprising a conditionlresponsive element and snap acting means operable thereby upon an abnormal condition afi'ecting said condition responsive. element.

8. In acontrol switch 01 the character described, an actuating arm, condition responsive means for controlling the position ct said actuating arm, coupling means for said actuating arm, a rocker arm, one end of said rocker arm being engageable with said coupling means, a contact unit, an actuating element therefor, said contact unit being adaptable to being alternatively mounted with said actuating element en- 4 gageable with and operable by said coupling meanaor with said actuating element engageablewith and operable by the other end. of said rocker arm, and an auxiliary control for said actuating element comprising a condition responsive element and snap acting means operable thereby upon an abnormal condition atiecting said condition responsive element.

' BURTON" E. SHAW. 

